So I have basically narrowed down my next synth-workstation to the korg triton extreme however I am not sure which i should get: 76 Keys, or 88 Keys. I am not sure about the weighted keys. I am very much used to playing regular synth keys and not to fond about playing the weighted keys, however I wouldnt mind learning the feel of them. Now what is Aftertouch? And what else would I be benifiting from besides the aftertouch and weighted keys with the 88 version

All Triton versions have aftertouch, so that is no advantage exclusive to the 88 version.
Aftertouch is the capability to modulate a sound by pressing harder on a key you are already pressing. This modulation can be assigned to various types. One very common is to assign vibrato to aftertouch, so if you are playing a lead, and at some point you hold on a note/key and apply more pressure on that same note, then the aftertouch function kicks in and the vibrato is applied to the sound. So the function is fully programmable, you can do bends, turn on effects and much much more. It can help you alot on your expressive playing!

I guess the 88 version is a must if you are into piano playing or just used to the weighted keys, but otherwise I would go for the 76 version (like I did with my Triton Classic). Also the synth action on the Triton is very very nice so it is an excellent option aswell.

Go for the 88 man, The extra keys sometimes come in handy, and those weighted bloks are nothing but better for your playing, more expression and I have more precision with my arpeggios on weighted keys than on non-weighted.

Aftertouch is the capability to modulate a sound by pressing harder on a key you are already pressing.

Not quite - you're right in saying what you can do with it, but aftertouch isn't a modulation source in itself, in the same way that an LFO can be. It's basically just another type of controller, like a ribbon or fader that always starts and ends its use at 0, rather than a 'pure' modulation source.

Thanks alot! Now I was in my local music store and they have the 76 key on display, but no 88 so I can get the feel of the weighted keys. What keyboard would you compare the weighted action to? I played the Yamaha s90 which to me has a very real action and then I played the Fusion which doesnt have as much action...

Not quite - you're right in saying what you can do with it, but aftertouch isn't a modulation source in itself, in the same way that an LFO can be. It's basically just another type of controller, like a ribbon or fader that always starts and ends its use at 0, rather than a 'pure' modulation source.

~Loki, the nitpicker :P

Totally right! My mistake!

Attack keys is right, you can develop more expression playing on 88's, but I will dare to say that it applies mostly for piano and piano-like sounds including bells and similar. I would say playing other type of sounds will be pretty much the same or even better on semiweighted, like organ patches. Personally I prefer semiweighted for leads, pads, strings... but that's just me.
I guess just think on what type of sounds and playing you use the most and choose the actions that suits better for your needs.
Also if you feel more comfortable with the 76's feel, go for it and don't worry about those extra keys the 88 has, is just not worth the money.

Right, but what about the action or the weighted keys? Is it more like the action of the fusion or like the s90....personally I think the s90 was too much for me, but the fusion was pretty nice...

Thanks alot

I owned the TEx88 for 2 years, and the action is considerably lighter than on the S90, so it´s definitely closer to the action of the Fusion. If you´ve never really played on piano-action boards the switch to the 88 Extreme will probably not be that big. Personally I found the action quite a bit too light for playing piano comfortably (always felt like I had to hold back not to reach full velocity too soon), but then again, I grew up playing on a Bechstein upright piano, and to this day I´ve never layed hands on a heavier action than that ;-)
What you might also consider when choosing between the 76 and the 88 is the total weight of the board. The 88 is a LOT heavier. This was the reason why I sold mine, as the TEx88 plus hardcase weighs in at nearly 50kg, and unfortunately there´s not always somebody to help you carry it. Bottom line is, when you´re planing on moving your new board a lot and you´re not really into playing piano-sounds most of the time (and not used to it and so somewhat "spoiled"), you might be better of with the 76.